As in [1]}, we have used the iterative Singular Spectrum Analysis algorithm (iSSA) to extract the components, mainly the annual one, in each grid cell and as a function of time. For the iSSA method, see [2]}, for properties of the Hankel and Toeplitz matrices, see [3]} and for the Singular Value Decomposition (SVD) algorithm, see [4]}. For summaries of how we use them, the reader is referred to [5]}.
